The invention relates to improvements in apparatus for processing one or more tows of filamentary filter material, particularly for processing one or more tows of filamentary material which can be used to filter tobacco smoke in filter cigarettes, cigars, cigarillos and/or other rod-shaped articles of the tobacco processing industry. Still more particularly, the invention relates to improvements in apparatus which are provided with means for stretching, selectively softening and gathering running tows of filamentary filter material prior to conversion of the thus treated tows into substantially rod-shaped fillers ready to be draped into webs of cigarette paper, artificial cork or other wrapping material. The resulting filter rods are thereupon severed at regular intervals to yield filter mouthpieces of unit length or multiple unit length, and such mouthpieces can be put to storage or are delivered directly to so-called tipping machines to be assembled with plain cigarettes, cigars, cigarillos or other rod-shaped tobacco containing products into filter cigarettes, cigars, cigarillos or other filter tipped rod-shaped articles of unit length or multiple unit length.